EEG is the only technique listed in the possible answers section capable of monitoring an electrical current. EEGs, electroencephalograms, are amplified waves of the electrical activity that are found along the surface of the brain. 

The control group in an experimental procedure is designed to provide an unaltered comparison to the experimental or treatment group. The control group in a study of the effects of a vegetarian diet would eat a normal, non-vegetarian diet (or whatever diet the animals ordinarily receive at the zoo).

Independent variables cause change in the dependent variable of an experiment. In this experiment, food spiciness would cause a change in the dependent variable—exercise performance. This variable was changed throughout the experiment in order to measure the induced effect on the subject’s ability to exercise. Remember that while spiciness is sometimes seen as a matter of personal taste, there is at least one quantitative system for measuring it: the Scoville scale.

Dr. Schwab is using a behavioral assessment. He is identifying and measuring target behaviors and their controlling variables in an individual's natural environment.

A placebo is an inert substance that participants believe is the actual treatment or drug. Placebos have been found to be, in some cases, effective in treatment, and they have also been used to test the efficacy of drugs.

A between-subjects design involves using different participants in the control and experimental groups. There is no overlap in the conditions. Within-subjects design uses the same participants in multiple treatments.

Surveys rely solely on answers that were given to the participants therefore in certain categories (like in sex studies) subjects may give false answers in order to maintain social order. Although it is difficult to get a representative sample of the population, it is possible to get a sample that is large enough and random enough to represent the whole population. Survey questions can readily be made to be objective. Surveys are relatively easy to perform once participation is addressed.

Since case studies only involve one situation, they may lead to the over-generalization of a condition that is rare and/or specific to a certain situation. 

This example is a double blind study. In a double blind study, both the subjects and researchers do not know which individuals are given the placebo and which are given the actual treatment. This type of study can control for the placebo effect and researcher bias. 

The population would be all the college students that have taken standardized tests in the country the psychologist resides in because a population is all the possible individuals in a group that a sample can be pulled from. It is most likely not possible that the researcher would be able to include the entire population in his study due to the large size.